PTT signalling using Soundcard/DSP drivers

There seems to be some confusion on how drive PTT with my Soundcard and DSP driver. So here are some instructions on how to do it

SoundBlaster and Compatible drivers
WindowsSoundSystem (WSS) and Compatible drivers
Personal Sound Architecture (PSA) Soundcards
Texas Instruments TMS320C26 and TMS320C50 DSP Starters Kits (DSK)
Analog Devices EZKIT Lite

The Parallel Port Solution

[Schematic PTT using Parallel Port]

The Serial Port Solution

[Schematic PTT using Serial Port]

The Game Port Solution

[Schematic PTT using Game Port]

The Vox Circuitry

[Schematic PTT using Vox circuitry]

Please note that the Vox circuitry should only be used for 1200 baud AFSK. It is not well suited for 9600 baud FSK

You must adjust the output level of the right channel to the highest possible volume in order to have enough signal voltage to turn on the MOSFET transistor.

Note: Instead of a BC237, most general purpose small signal NPN transistors may be used as well, such as the BC547 or 2N2222.

Thomas Sailer --